1. Field of the Invention
This invention relates to a particle dispensing apparatus which are used for supplying powdered particles such as developing a agent to image forming systems such as, for instance, electronic copying machines.
2. Discussion of Background
Generally, in the case of electronic copying machines, toner is normally supplied when required to the developer of a developing system in order to make the toner density in the developing agent uniform.
Hitherto, as shown in simplified FIG. 1, this kind of electronic copying machine has been designed as follows. Drum-shaped photosensitve body 2, which is free to rotate, is provided as an image carrier which is pivoted so that it is free to revolve approximately in the centre of system cabinet 1. This photosensitive body 2 is uniformly charged by charging charger 3. At the same time, an electrostatic latent image of an original document (not illustrate) illustrated, which is placed on original document platform 4 made of transparent glass, is formed on photosensitive body 2 via optical system, 5 which is composed of exposure lamp 5a, 1st, 2nd and 3rd reflecting mirrors 5b, 5c and 5d, lens 5e and 4th reflecting mirror 5f. This electrostatic latent image is developed by coating the developing agent from a developing system which is described later.
This image is transported towards copying charger 6. This copying charger 6 copies the developed image on the copy paper P, which is ordinary paper used as recording paper and has been supplied automatically or manually from paper supply cassette 7 and transported via paper supply rollers 8 and resist-roller pair 9 and 9. The paper is peeled by peeling charger 10 using an AC corona discharge. After copying, copy paper P is peeled from photosensitive body 2 and the developed image passes along transport path 11 and is fuse-fixed by fixing device 12. The paper is then dispensed on the paper dispense tray 14 by dispensing roller pair 13a and 13b.
Then, after the copying of the developed image on to copy paper P and peeling, any developing agent remaining on photosensitive body 2 is cleaned off by cleaning device 15. The potential on photosensitive body 2 is controlled to below a specified level by discharging lamp 16 and photosensitive body 2 is thus ready for the next copying operation.
Developing system 20, which develops the electrostatic latent image formed on photosensitive body 2 in this way, is constructed by 1st and 2nd developers 21 and 21 which form a vertical pair in which different colours of developing agents, for instance red and black, are respectively contained. Each of these developers 21 is composed of developing roller 22, which is a rotating sleeve fitted over a magnetic roller with a number of magnetic pole pieces, and agitator roller 23 which agitates developing agent in developer 21. At the same time, a toner supply device 30 is provided in each of developers 21.
Toner supply device 30 operates when the toner density in the developing agent, which is detected by a sensor (not illustrated) is below a specified level, and thus supplies toner T.sub.0 to developer 21. The construction of toner supply device 30 is as follows. As shown in FIGS. 2 to 4, transport guide 31, with a U-shaped cross-section, is provided running between side-frames 21a and 21b of developer 21. A number of supply apertures 32 are opened in the bottom of transport guide 31 so that toner T.sub.0 is supplied by dropping. At the same time, transport auger 33 is pivoted in transport guide 31 so that it is free to rotate under the drive of a driving system (not illustrated). By the unidirectional rotation under drive of transport auger 33, toner T.sub.0 supplied through a entrance port E from toner hopper 34, which is provided to one side of transport guide 31, is transported in the axial direction (shown by the solid line arrow in FIG. 2) and is supplied to developer 21 by dropping from each of supply apertures 32.
However, in the case of toner supply device 30 in this type of conventional developing system 20, both ends 31a and 31b of transport guide 31 and spindle 33a of transport auger 33 are secured between both side frames 21a and 21b on developer 21. At the same time, as shown in FIG. 3, the positions of the upper edges of transport guide 31, which is supported so that transport auger 33 is enclosed, are, for example, regulated by pressure plate 40 which also acts as a cover for developer 21. Transport guide 31 is normally made of a metal such as aluminum or a synthetic resin such as ABS resin, with a thickness of 1.about.3 mm. Also, as shown in FIG. 4, normally supply apertures 32 are opened as aperture or slit shapes whose diameters W.sub.0 are 1.about.3 mm.
For this reason, hitherto, since inside walls 32a with depth d of approximately 1.about.3 mm are formed in supply apertures 32 opened in transport guide 31, the toner is held on inside walls 32a of supply apertures 32 by aggregation due to the charge on toner T.sub.0, whose mean particle size is 10.mu.m, and fluidity due to temperature, and tends to clog so that a smooth toner supply can not be provided.
Moreover, as a means of solving the above disadvantage, enlargement of supply apertures 32 may be considered. However, when using this method, the amount of toner supplied increases so that the agitation in developer 21 by agitator roller 23 can not be sufficiently carried out. Thus, not only do faults such as spattering occur easily, but also, since toner T.sub.0 can not be transported as far as the end of transport guide 31, there has been a problem with so-called `one-sided` toner dropping.